1. Field of the Invention
The present invention relates to a control system and a method thereof for a vehicle, and more particularly, to a control system to prevent a vehicle from deviating from a lane and a method thereof.
2. Description of the Related Art
A significant amount of research is being performed on control methods and systems for automatically driving vehicles with limited or no driver operation. That is, with the use of electrical sensors that perform various detections in place of what the driver would perceive, differing states of vehicle surroundings and of the vehicle are determined to perform automatic driving of the vehicle. Two of the most difficult aspects of such automatic control are maintaining a specific distance from a vehicle in front of the vehicle being automatically controlled, and preventing deviation from the lane in which the automatically-controlled vehicle is traveling.
In the case of automatic lane deviation prevention, a Gaussian detection method is used. In more detail, lane markers are detected from images obtained by a CCD camera mounted to the vehicle, and it is determined whether the vehicle is deviating from the lane from an angle between left and right lane markers. A warning is typically provided to the driver if the vehicle is deviating from the lane.
Conventional lane marker detection and lane deviation detection is described with reference to FIGS. 6 and 7.
A CDF (Cumulative Distribution Function) is first obtained from input images. In the CDF, points with the largest values in the left and right regions on a basis of 90 degrees are determined to be left and right lane markers. Then, by comparing an amount of deviation from a center of the lane with a predetermined value xcex4, it is determined whether the vehicle is deviating from the lane. The amount of deviation from the center of the lane is set as a difference between a center value of a left lane marker slant angle and a right lane marker slant angle and 90 degrees. If the difference is greater than the predetermined value xcex4, it is determined that the vehicle is deviating from the lane and a lane deviation warning is output.
According to the above method, substantially precise determinations of the lane deviation may be made in an area where the road is substantially straight. However in areas where there is a curve in the road, the amount of deviation from the center of the lane of the above method varies according to changes in the amount of curvature and a width of the vehicle. Accordingly, accurate determinations of whether the vehicle is deviating from the lane may only be made in straight sections of the road. In locations where there is a substantial curve in the road as shown in FIG. 7, it may be incorrectly determined that the vehicle is deviating from the lane, in which case a warning may be output to the driver when the vehicle is driving safely, fully within the lane.
The present invention is a method for preventing a vehicle from deviating from a lane, in which precise determinations of lane deviation can also be made when driving on a curved road.
To achieve precise determinations of lane deviation on a curved road, the present invention prevents a vehicle from deviating from a lane that uses a DSRC (dedicated short range communication) system, which is a system enabling communication between a vehicle and roadside equipment, to receive a curvature of the road and lane width before the vehicle travels in the corresponding section of road. This road information and setting information of a camera mounted on the vehicle are then used to determine a lane deviation determination standard angle, which is used in curved sections of the road. An absolute value of a difference between the standard angle and a center value of left and right lane marker angles is compared with a value xcex4 to determine whether the vehicle is deviating from the lane.
In more detail, the control method for preventing lane deviation of a vehicle comprises determining a lane deviation determination standard angle; determining a center value of a left lane marker slant angle and a right lane marker slant angle; calculating an absolute value of a difference obtained by subtracting the lane deviation determination standard angle from the center value of the left and right lane marker slant angles; determining if the absolute value of the difference is greater than a predetermined critical value; and determining that the vehicle is deviating from the lane if the absolute value of the difference is greater than the predetermined critical value.
Preferably, the lane deviation determination standard angle is determined from road information including a road curvature and a lane width, and from information obtained from a camera mounted on the vehicle including camera position information and a photographing angle of the camera.
Further, it is preferable that the critical value is determined based on the lane width.
The present invention is also a system for preventing lane deviation of a vehicle comprising: a camera for photographing an area in front of the vehicle; roadside equipment having data on a road curvature and a lane width; onboard equipment for determining a lane deviation determination standard angle using data on the road curvature and the lane width input from the roadside equipment and data on a position of the camera and a photographing angle of the camera; and a lane deviation warning system ECU for determining whether the vehicle is deviating from the lane using the lane deviation determination standard angle and an image photographed by the camera.